Curtain shutter for photographic cameras

ABSTRACT

A curtain shutter for photographic cameras including an edge member having a U-shaped groove for holding one end of an opaque curtain, the other end of which is secured to and wound around one of the curtain drums of the shutter, the edge member having at both the upper and lower ends thereof a projecting portion extending beyond the upper and lower longitudinal edges of the opaque curtain, respectively, and being provided with a slot at the bottom of the U-shaped groove in each of the upper and lower projecting portions and also with an extension strip integrally connected to one side wall of the edge member. An exposure slit is formed by the opaque curtain in cooperation with the edge member. The other end of each ribbon is inserted into the Ushaped groove through one of the said slots and turned in U-shape around the side wall of the edge member opposite the side wall on which the extension strip is provided. The turned end portions of the ribbons are adhesively secured to the outer surface of the edge member and also to the respective ribbon portions disposed outwardly of the slots. The extension strip is turned onto the turned end portion of the ribbon to cover at least a portion thereof.

United States Patent 1191 Noritake 1451 May 29, 1973 1541 CURTAIN SHUTTER FOR PHOTOGRAPHIC CAMERAS [75] Inventor: Mitsuo Noritake,Osaka,Japan [73] Assignee: Minolta Camera Kabushiki Kaisha,

Osaka-shi, Osaka-fa, Japan [22] Filed: Aug. 11, 1972 v [21] Appl.No.: 279,814

- [52] US. Cl. ..95/57 Primary Examiner-Samuel S. Matthews Assistant Examiner-Russell E. Adams, Jr. Attorney-Watson, Cole, Grindle & Watson [5 7 ABSTRACT A curtain shutter for photographic cameras including an edge member having a U-shaped groove for holding one end of an opaque curtain, the other end of which is secured to and wound around one of the curtain drums of the shutter, the edge member having at both the upper and lower ends thereof a projecting portion extending beyond the upper and lower longitudinal edges of the opaque curtain, respectively, and being provided with a slot at the bottom of the U- shaped groove in each of the upper and lower projecting portions and also with an extension strip integrally connected to one side wall of the edge member. An exposure slit is formed by the opaque curtain in cooperation with the edge member. The other end of each ribbon is inserted into the U-shaped groove through one of the said slots and turned in U-shape around the side wall of the edge member opposite the side wall on which the extension strip is provided. The turned end portions of the ribbons are adhesively secured to the outer surface of the edge member and also to the respective ribbon portions disposed outwardly of the slots. The extension strip is turned onto the turned end portion of the ribbon to cover at least a portion thereof.

2 Claims, 6 Drawing Figures BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a curtain shutter for photographic cameras, and more particularly to an edge member for connecting an opaque curtain with ribbons in curtain shutters.

A curtain shutter for photographic cameras generally includes an opaque curtain having one end thereof securely connected to and wound around one of the curtain drums of the shutter and a pair of ribbons each having one end thereof securely connected to and wound around the other curtain drum, the other end of each ribbon being connected to the free end of the opaque curtain. V

An edge member is generally used to make the connection between the opaque curtain and the two ribbons as secure as possible to endure repeated use.

The edge member has a groove of U-shaped crosssection for inserting thereinto the free end of the opaque curtain. The thus inserted curtain end is adhesively secured to the inner walls of the edge member before the side walls of metal are pressed toward each other in order to securely grip the curtain therebetween.

The upper and lower ends of the edge member are extended outwardly beyond the upper and lower longitudinal edges of the opaque curtain for securing thereto the free ends of the ribbons. As an example of one means for providing secure connection between the edge member and the ribbons, a slot is formed at the bottom of the U-shaped groove in each of the upper and lower outwardly extended portions of the edge member for inserting therethrough the free endsof the ribbons. Each free end of a ribbon is threaded through the corresponding slot and turned around one of the side walls of the edge member. The turned end portion of the ribbon is adhesively secured to the outer surface of the edge member and to 'the side of the ribbon portion extending outwardly from the slot toward one of the curtain drums.

With the above construction, the ribbons and the opaque curtain are securely connected to each other by means of the edge member. However, the curtain has.

a relatively large thickness and mass in the locality of the connection between the ribbons and the edge memher since the connection consists of four layers, i.e., the two side walls of the edge member forming the U- shaped groove, the ribbon portion interposed between the two side walls and the ribbon end. portionturned and adhered to the outer side of the edge member. This causes a fluttering phenomenon when the curtain is' driven upon release of the shutter, with the result that the connection is brought into contactat a high speed with other parts of the camera such as the exposure frame and the mirror box, leading to accidents'such as breakage of the connection due, to wear of the turned end portion of the ribbon and separation of the adhesion between the edge member and the ribbons.

These accidents may be prevented by covering'or coating the outer surface of the turned end portion of each ribbon with a wear resistant material such as metal.

THE OBJECT OF THE INVENTION It is an object of the present invention to provide a curtain shutter for photographic cameras, having a rigid and durable connection between the opaque curtain and the ribbons forming the exposure slit of the shutter.

Another object of the invention is to provide a curtain shutter for photographic cameras wherein the opaque curtain and the ribbons are connected by means of an edge member of metal and the outer side of the connection is covered with a metal strip integrally formed with the edge member.

Still another object of the invention is to provide a curtain shutter for photographic cameras, having the connection between the opaque curtain and the ribbons protectively covered with a metal strip, the shutter being of a simple construction which allows easy assembling and manufacture.

SUMMARY OF THE INVENTION According to the present invention, there is provided a curtain shutter for photographic cameras comprising an edge member of metal having two side walls forming therebetween a U-shaped groove for holding one end of an opaque curtain, the other end of which is secured to and wound around one of the curtain drums of the shutter, said edge member being provided at both the upper and lower ends thereof with a portion extending outwardly and widthwise of said opaque curtain and each having a slot formed along the bottom of the U- shaped groove, and extension strips integrally formed with the portions extending outwardly from one of the side walls of the edge member; a pair of ribbons each having one end thereof securely connected to and wound around the other curtain drum of the shutter, the other end of each ribbon being inserted into the U- shaped groove through a slot and turned around the side wall of the edge member on the side opposite to the side wall from which the extension strips are projected, the turned end portion of each ribbon being securely adhered onto the outer surface of the side wall around which the ribbon is turned, and to the ribbon portion disposed outwardly of said slot by means of an adhesive agent, and the corresponding strip being turned over the outer surface of the turned end portion of the ribbon to cover at least a portion thereof. One of the features of the present invention resides in that the end portion of the opaque curtain and the ribbons connected by the edge member are protectively covered by the metal edge member and the extension strip.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a fragmentary transverse cross-section showing a camera construction incorporating the curtainshutter according to the present invention; I

FIG. 2 is a fragmentary perspective view showing the connection between the opaque curtain and the ribbon in a known shutter;

FIG. 3 is a fragmentary perspective view showing the connection between the opaque curtain and the ribbon in the curtain shutter of the present invention;

FIG. 4 is a top view corresponding to FIG. 3;'

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 3; and

FIG. 6 is a perspective view of the edge member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

A preferred embodiment of the invention will now be described with reference to the accompanying drawings wherein like numerals are used throughout the various views to designate like parts. In FIG. 1, the front curtain 2 of the curtain shutter is stretched between two curtain drums 6 and 7 which are rotatingly movable with respect to the body of the camera. More particularly, the opaque curtain 2 is secured at one end thereof to the front curtain drum 6 and wound thereon. The other or free end of the opaque curtain is connected to a metal edge member 4. Also connected to this edge member 4 are free ends of the upper and lower ribbons 5 which have the other ends thereof securely connected to and wound around the other front curtain drum 7.

A rear curtain of the shutter, which is not shown in the drawings for simplicity of illustration, has also an opaque curtain which is secured at one end thereof to a rear curtain drum similar to the front curtain drum 7 and wound thereon. The other or free end of the rear opaque curtain is secured to an edge member to which are connected the free ends of the two ribbons. The other ends of the ribbons are secured to and wound around the other rear curtain drum parallel with respect to the front curtain drum 6. The front curtain drum 6 and the rear curtain drum provided in parallel to the front curtain drum 6 are biased to wind the curtains thereon. FIG. 1 shows the curtain shutter in the cocked position where the curtain is wound around the curtain drum 7 against the winding force of the other curtain drum 6. The curtain may be released from the cocked position by means of a releasing member which is not shown, and wound around the drum 6 at a high speed under the influence of the winding force of the curtain drum 6 to initiate the exposure operation. The rear curtain is also wound up by the rear drum on the side of the drum 6 in a similar manner and is released at a delayed time using a known time delaying mechanism to complete the exposure of the film.

The partition wall 8 holding the film reel 11 in position is extended rearwardly of the curtain shutter, the fore end of the partition wall forming an exposure frame 9. The film 12 wound on the reel 11 is pressed against the back surface of the exposure frame 9 by means of a pressing plate member which is supported on the lid 13 of the camera by means of a spring 14.

It has been the conventional practice to connect the opaque curtain and the two ribbons 5 by way of an edge member in the manner shown in FIG. 2.

More particularly, the edge member 4' is formed by longitudinally folding an elongated thin metal sheet having a length slightly greater than the width of the opaque curtain to form a cross-sectionally U-shaped groove defined by two side walls 4a and 4'b. The free end of the opaque curtain is inserted into the U-shaped groove and adhered to the inner wall surfaces of the edge member 4. The two side walls 4'0 and 4'b are thereafter pressed toward each other to securelyclamp the free end of the opaque curtain in the U-shaped groove. The edge member 4 has, at the upper and lower ends thereof, upper and lower portions extending outwardly and widthwise with respect to the opaque curtain, respectively.

Each ofthe upper and lower portions of the edge member has a slot 4'c formed at the bottom of the U- shaped groove for inserting thereinto the free end of a ribbon 5. The foreend portion 5a of the ribbon 5 which has been inserted through the slot 4'c is turned around the side wall 4a and adhered to the outer surface of the side wall 4a and to the ribbon portion disposed outwardly of the slot 4'c as shown at 5b.

With the conventional curtain shutter construction as described above, the projecting portion of the edge member becomes very thick due to overlapping of various parts such as the side wall 4b, ribbon portion 5 within the U-shaped groove, side wall 4a and the turned end portion 5a of the ribbon, and moreover, the turned end portion 5a of the ribbon is exposed so that if fluttering occurs, when the curtain is driven by the curtain drum 6 in the manner as described hereinabove, causing the projecting portion of the edge member to hit on various parts of thecamera including the edge of the exposure frame 9 and the mirror box 10, this often results in breakage of the turned end portion 5a of the ribbon due to abrasive wear and also in separation of the adhesion between the ribbon 5 and the side wall 4a.

Whereas, according to the present invention, there is employed an edge member as shown in FIG. 6. This edge member is provided in the projecting portion thereof with an extension strip 4d which is formed integrally with and extending outwardly from one of the side walls 44 and 4b of the U-shaped groove. As shown in FIGS. 3 to 5, the free end of the opaque curtain is inserted into the U-shaped groove of the edge member 4 except for the upper and lower projecting portions thereof. The free end of the opaque curtain is adhered to the edge member 4 by means of a suitable adhesive agent before the side walls 4a and 4b are pressed toward each other to clampingly retain the curtain therein, in the same manner as described in conjunction with FIG. 2.

On the other hand, the ribbon 5 inserted into the U- shaped groove in the projecting portion of the edge member through the slot 4c formed therein is turned around the side wall 4a which faces the side wall 4b having the extension strip 4d. The turned end portion 5a of the ribbon is adhered to the outer side of the side wall 4a and the foremost end 5b of the turned end portion 5a is adhesively secured to a portion of the ribbon 5 which is disposed outwardly of the slot 4c of the U- shaped groove.

The extension strip 4d of the side wall 4b is turned along the turned end portion 5a of the ribbon 5 to protectively cover the outer surface thereof.

Thus, the extension strip 4d is preferred to have a width and a length sufficient for covering substantially the whole area of the outer surface of the turned end portion 5a of the ribbon 5. However, the extension strip 4d may have a length to cover the turned end portion 5a as well as the digital end 5b of the ribbon 5.

Though the foregoing description has been presented mainly in conjunction with the front curtain, it will be understood that the same construction may be applied to the rear curtain and that the rear curtain employing such construction duly falls within the scope of the present invention.

I claim:

1..A curtain shutter for photographic cameras comprising:

an opaque curtain having one end thereof secured to one of the curtain drums of the shutter of the camera and wound around said curtain drum;

a pair of ribbons each having one end thereof securely connected to the other one of the curtain drums of the shutter in positions corresponding to the upper and lower longitudinal edges of the opaque curtain;

an edge member having a length greater than the width of said opaque curtain and the distance between the two ribbons, said edge member being formed by folding an elongated sheet metal strip upon itself to form a cross-sectionally U-shaped groove defined by two opposing side walls for receiving and securing therebetween the other end of the opaque curtain; said edge member having projecting portions provided at the upper and lower ends thereof;

a slot formed at the bottom of the U-shaped groove in each of the upper and lower projecting portions of the edge member for inserting therethrough the other ends of said ribbons, the inserted end porportion of the ribbon.

II it t i 

1. A curtain shutter for photographic cameras comprising: an opaque curtain having one end thereof secured to one of the curtain drums of the shutter of the camera and wound around said curtain drum; a pair of ribbons each having one end thereof securely connected to the other one of the curtain drums of the shutter in positions corresponding to the upper and lower longitudinal edges of the opaque curtain; an edge member having a length greater than the width of said opaque curtain and the distance between the two ribbons, said edge member being formed by folding an elongated sheet metal strip upon itself to form a cross-sectionally U-shaped groove defined by two opposing side walls for receiving and securing therebetween the other end of the opaque curtain; said edge member having projecting portions provided at the upper and lower ends thereof; a slot formed at the bottom of the U-shaped groove in each of the upper and lower projecting portions of the edge member for inserting therethrough the other ends of said ribbons, the inserted end portions of the ribbons being turned around one of said side walls of the edge member and adhered to the outer surface thereof; and an extension strip provided on the edge of the other of said side walls and turned along the turned end portion of the ribbon to cover at least a portion of the outer surface thereof.
 2. A curtain shutter as defined in claim 1, wherein said extension strip has a width larger than that of said ribbon and a length sufficient for covering substantially the whole area of the outer surface of the turned end portion of the ribbon. 